1. Field of the Invention
This invention relates generally to thermal testing, and more particularly to a cast virgin Teflon, viz., polytetrafluoroethylene or PTFE, liner to be placed in a test cylinder in an apparatus for thermal testing of oil well drilling mud and additives samples.
The present invention may be used in a testing apparatus such as that disclosed in Schroeder U.S. Pat. No. 4,677,843.
2. Brief Description of the Prior Art
Pertinent references in the prior art include Noteboom U.S. Pat. No. 3,941,661; Lynn U.S. Pat. No. B1 4,238,568; Keilman U.S. Pat. No. 4,717,668; and Mussi U.S. Pat. No. 4,912,058.
Noteboom U.S. Pat. No. 3,941,661 discloses a plastic spiral insert for use in roller culture bottles for cell culture. Lynn U.S. Pat No. B1 4,238,568 discloses a roller bottle having a plurality of sections which may be bonded after their interior surfaces have been treated to enhance cell adhesion. Keilman U.S. Pat. No. 4,717,668 discloses a plastic roller bottle for suspension cultures for bacteriology or other cell growth or maintenance. Mussi U.S. Pat. No. 4,912,058 discloses a roller bottle with provision for increased internal surface area for cell growth by the use of a foamed, textured or woven liner or sleeve into the bottle prior to use.
Each of these prior art references has the obvious limitation, compared to the present invention, of applying only to cell culture growth; they are not comparable to devices for testing samples at elevated temperature conditions.
The present invention is distinguished over the prior art in general, and these patents in particular, by a cast virgin Teflon liner for steel test cylinders used in thermal testing of a sample of drilling mud or additives. The liner has a hollow cylindrical body closed at one end and open at the other. A disc-shaped lid fits inside the open end of the liner and an elastomeric o-ring makes a tight seal between the liner and lid. A threaded hole in the center of the lid is closed with threaded plug. The apparatus includes a threaded metal tool or puller with T-shaped handle, for removing the liner from the test cylinder, and also for removing the lid from the liner. An internal air passageway in the puller from a first opening in the tip end of the puller to a second opening on one side of the shaft allows the lid to be removed from the liner without creating a vacuum in the space between the sample and the lid. For removing the liner from the test cylinder, the threaded shaft is screwed into the lid such that the second opening is covered and thereby creates a vacuum between the sample and lid when the liner is pulled out of the test cylinder. The liner and lid are made of cast virgin Teflon to avoid dangerous chemical reactions, e.g., oxidative reactions, with carbon particles in molded or reused Teflon.